[R] Create matrix with subset from unlist
David Winsemius
dwinsemius at comcast.net
Fri Jan 29 16:17:22 CET 2010
On Jan 29, 2010, at 9:45 AM, Dennis Murphy wrote:
> Hi:
>
> The problem, I'm guessing, is that you need to assign each of the
> matrices
> to an object.
> There's undoubtedly a slick apply family solution for this (which I
> want to
> see, BTW!),
I don't have a method that would assign names but you could populate
an array of sufficient size and dimension. I populated a three-element
list with his data:
> dput(x)
list(structure(list(V1 = c(-27.3, 29), V2 = c(14.4, -38.1)), .Names =
c("V1",
"V2"), class = "data.frame", row.names = c("1", "2")), structure(list(
V1 = c(14.4, -38.1), V2 = c(29, -3.4)), .Names = c("V1",
"V2"), class = "data.frame", row.names = c("1", "2")), structure(list(
V1 = c(29, -3.4), V2 = c(-38.1, 55.1)), .Names = c("V1",
"V2"), class = "data.frame", row.names = c("1", "2")))
> xx <- array( , dim=c(2,2,3))
> xx[,,1:3] <- sapply(x, data.matrix)
> xx
, , 1
[,1] [,2]
[1,] -27.3 14.4
[2,] 29.0 -38.1
, , 2
[,1] [,2]
[1,] 14.4 29.0
[2,] -38.1 -3.4
, , 3
[,1] [,2]
[1,] 29.0 -38.1
[2,] -3.4 55.1
Without the more complex structure ready to accept the 2x2 arrays I
got this:
> sapply(x, data.matrix)
[,1] [,2] [,3]
[1,] -27.3 14.4 29.0
[2,] 29.0 -38.1 -3.4
[3,] 14.4 29.0 -38.1
[4,] -38.1 -3.4 55.1
--
David.
> but here's the brute force method using a loop:
>
> nms <- paste('x', 1:32, sep = "")
> for(i in seq_along(nms)) assign(nms[i], x[[i]])
>
> HTH,
> Dennis
>
> On Fri, Jan 29, 2010 at 6:30 AM, Muhammad Rahiz <
> muhammad.rahiz at ouce.ox.ac.uk> wrote:
>
>> Hello all,
>>
>> I'm trying to create a 2x2 matrix, 32 times after unlist() so that
>> I can
>> convert the list to matrix. I've looked through the R archive but
>> couldn't
>> find the answer. There is what I've done.
>>
>>
>>> f <- system("ls *.txt", intern=TRUE)
>>> x <- lapply(f, read.table)
>>> x
>> [[1]]
>> V1 V2
>> 1 -27.3 14.4
>> 2 29.0 -38.1
>>
>> [[2]]
>> V1 V2
>> 1 14.4 29.0
>> 2 -38.1 -3.4
>>
>> [[3]]
>> V1 V2
>> 1 29.0 -38.1
>> 2 -3.4 55.1
>>
>> [[4]]
>> V1 V2
>> 1 -38.1 -3.4
>> 2 55.1 -1.0
>>
>> [[5]]
>> V1 V2
>> 1 -3.4 55.1
>> 2 -1.0 21.9
>>
>> [[6]]
>> V1 V2
>> 1 55.1 -1.0
>> 2 21.9 -10.9
>>
>> ...
>>
>>> xx <- unlist(x)
>> V11 V12 V21 V22 V11 V12 V21 V22 V11 V12 V21 V22
>> -27.3 29.0 14.4 -38.1 14.4 -38.1 29.0 -3.4 29.0 -3.4 -38.1
>> 55.1
>> V11 V12 V21 V22 V11 V12 V21 V22 V11 V12 V21 V22
>> -38.1 55.1 -3.4 -1.0 -3.4 -1.0 55.1 21.9 55.1 21.9 -1.0
>> -10.9
>> V11 V12 V21 V22 V11 V12 V21 V22 V11 V12 V21 V22
>> -1.0 -10.9 21.9 -7.8 21.9 -7.8 -10.9 -48.2 -10.9 -48.2 -7.8
>> -44.9
>> V11 V12 V21 V22 V11 V12 V21 V22 V11 V12 V21 V22
>> -7.8 -44.9 -48.2 -43.8 -48.2 -43.8 -44.9 -10.3 -44.9 -10.3 -43.8
>> 44.2
>> V11 V12 V21 V22 V11 V12 V21 V22 V11 V12 V21 V22
>> -43.8 44.2 -10.3 -0.5 -10.3 -0.5 44.2 96.7 44.2 96.7 -0.5
>> -32.0
>> V11 V12 V21 V22 V11 V12 V21 V22 V11 V12 V21 V22
>> -0.5 -32.0 96.7 -0.2 96.7 -0.2 -32.0 -38.6 -32.0 -38.6 -0.2
>> 73.6
>> V11 V12 V21 V22 V11 V12 V21 V22 V11 V12 V21 V22
>> -0.2 73.6 -38.6 -17.5 -38.6 -17.5 73.6 -57.8 73.6 -57.8 -17.5
>> 10.7
>> V11 V12 V21 V22 V11 V12 V21 V22 V11 V12 V21 V22
>> -17.5 10.7 -57.8 -33.4 -57.8 -33.4 10.7 46.1 10.7 46.1 -33.4
>> 26.7
>> V11 V12 V21 V22 V11 V12 V21 V22 V11 V12 V21 V22
>> -33.4 26.7 46.1 -37.3 46.1 -37.3 26.7 1.2 26.7 1.2 -37.3
>> 36.3
>> V11 V12 V21 V22 V11 V12 V21 V22 V11 V12 V21 V22
>> -37.3 36.3 1.2 39.6 1.2 39.6 36.3 31.0 36.3 -27.3 39.6
>> 14.4
>> V11 V12 V21 V22 V11 V12 V21 V22
>> 39.6 29.0 31.0 -38.1 31.0 -3.4 -27.3 55.1
>>
>>
>> The output should be
>>
>> [[1]]
>> [,1] [,2]
>> [1,] -27.3 14.4
>> [2,] 29.0 -38.1
>>
>> [[2]]
>> [,1] [,2]
>> [1,] 14.4 29.0
>> [2,] -38.1 -3.4
>>
>> [[3]]
>> [,1] [,2]
>> [1,] 29.0 -38.1
>> [2,] -3.4 55.1
>>
>> ...
>> Thanks and much appreciated!
>>
>>
>>
>> Muhammad
>>
>> ______________________________________________
>> R-help at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide
>> http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
David Winsemius, MD
Heritage Laboratories
West Hartford, CT
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